Aside from being rich in valuable nutrients such as fiber, vitamins B and C, calcium, potassium, phosphorus, magnesium, selenium and zinc, mushrooms are also excellent sources of antioxidants, including some that are entirely unique to mushrooms. Ergothioneine and glutathione, both of which are found in mushrooms, are recognized as "master antioxidants" that inhibit oxidative stress. Both are considered important antiaging compounds.
As noted in The Guardian,1 "… [S]cientists think [ergothioneine and glutathione] may help to protect the body against the maladies of old age, such as cancer, coronary heart disease and Alzheimer's disease." Ergothioneine appears to have a very specific role in protecting your DNA from oxidative damage,2 while glutathione is important for successful detoxification of heavy metals and other contaminants.
According to Robert Beelman, Professor Emeritus of food science and director of Penn State Center for Plant and Mushroom Products for health:3
"[C]ountries that have more ergothioneine in their diets, countries like France and Italy, also have lower incidences of neurodegenerative diseases, while people in countries like the United States, which has low amounts of ergothioneine in the diet, have a higher probability of diseases like Parkinson's Disease and Alzheimer's.
Now, whether that's just a correlation or causative, we don't know. But, it's something to look into, especially because the difference between the countries with low rates of neurodegenerative diseases is about 3 milligrams per day, which is about five button mushrooms each day."
Porcini Mushrooms — An Antioxidant Powerhouse
While all edible mushrooms have beneficial properties, some are more potent than others. As noted by Beelman, " … [W]ithout a doubt, mushrooms are the highest dietary source of these two antioxidants taken together, and some types are really packed with both of them." When it comes to the antioxidants ergothioneine and glutathione, wild ceps (Boletus edulis4), commonly referred to as porcini mushrooms, contain the highest amounts.
Beelman and colleagues at Penn State measured levels of these two antioxidants in 13 different species of mushrooms, and wild porcini mushrooms were the clear winner.5,6,7,8 That said, even the white button mushroom contains more of these antioxidants than most other foods.
They also found that mushrooms high in glutathione are also high in ergothioneine, so the two appear to be correlated. More good news: Ergothioneine and glutathione are heat stable, so cooking your mushrooms does not significantly affect their health benefits.
Porcini Are Popular With Gourmet Chefs
With a strong, nutty flavor, porcini mushrooms are commonly found in Italian dishes and are a favorite among gourmet chefs. Mushroom-appreciation.com9 offers a number of recipes and serving suggestions for porcini mushrooms. The dense and meaty porcini mushroom cap can grow to a diameter of 12 inches, and a mature specimen can weigh as much as 2 pounds.
Wild porcini is found in hardwood forests, as they form a symbiotic relationship with trees. The mycorrhizal fungi with their hyphae (long, branching filamentous structures) help shuttle nutrients to the trees' roots, while the mushrooms are nourished by plant sugars. Porcini mushrooms are not mass cultivated since they're mycorrhizal and need the symbiotic relationship with other plants to thrive.
The best places to forage for wild porcini is near pine, chestnut, hemlock and spruce trees, during summer through fall. While Italy is famous for its porcini mushrooms, they can also be found in Europe, the U.S., New Zealand and even South Africa. Other types of mushrooms, such as the white button, can be more easily cultivated and are therefore less expensive than the wild porcini.
In the U.S., half of the nation's mushroom crop come from Chester County, Pennsylvania, where indoor farms produce more than a million pounds of mushrooms per day.10 It's important to eat only organically grown mushrooms, though, as they absorb and concentrate whatever they grow in, for better or worse. Mushrooms are known to concentrate heavy metals, as well as other air and water pollutants that can defeat their medicinal value.